/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 2003-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: AttributesImplSerializer.java,v 1.2.4.1 2005/09/15 08:15:14 suresh_emailid Exp $
 */

package com.sun.org.apache.xml.internal.serializer;

import java.util.Hashtable;

import org.xml.sax.Attributes;
import org.xml.sax.helpers.AttributesImpl;

/**
 * This class extends org.xml.sax.helpers.AttributesImpl which implements org.
 * xml.sax.Attributes. But for optimization this class adds a Hashtable for
 * faster lookup of an index by qName, which is commonly done in the stream
 * serializer.
 *
 * @xsl.usage internal
 * @see org.xml.sax.Attributes
 */
public final class AttributesImplSerializer extends AttributesImpl {

  /**
   * Hash table of qName/index values to quickly lookup the index
   * of an attributes qName.  qNames are in uppercase in the hash table
   * to make the search case insensitive.
   *
   * The keys to the hashtable to find the index are either
   * "prefix:localName"  or "{uri}localName".
   */
  private final Hashtable m_indexFromQName = new Hashtable();

  private final StringBuffer m_buff = new StringBuffer();

  /**
   * This is the number of attributes before switching to the hash table,
   * and can be tuned, but 12 seems good for now - Brian M.
   */
  private static final int MAX = 12;

  /**
   * One less than the number of attributes before switching to
   * the Hashtable.
   */
  private static final int MAXMinus1 = MAX - 1;

  /**
   * This method gets the index of an attribute given its qName.
   *
   * @param qname the qualified name of the attribute, e.g. "prefix1:locName1"
   * @return the integer index of the attribute.
   * @see org.xml.sax.Attributes#getIndex(String)
   */
  public final int getIndex(String qname) {
    int index;

    if (super.getLength() < MAX) {
      // if we haven't got too many attributes let the
      // super class look it up
      index = super.getIndex(qname);
      return index;
    }
    // we have too many attributes and the super class is slow
    // so find it quickly using our Hashtable.
    Integer i = (Integer) m_indexFromQName.get(qname);
    if (i == null) {
      index = -1;
    } else {
      index = i.intValue();
    }
    return index;
  }

  /**
   * This method adds the attribute, but also records its qName/index pair in
   * the hashtable for fast lookup by getIndex(qName).
   *
   * @param uri the URI of the attribute
   * @param local the local name of the attribute
   * @param qname the qualified name of the attribute
   * @param type the type of the attribute
   * @param val the value of the attribute
   * @see org.xml.sax.helpers.AttributesImpl#addAttribute(String, String, String, String, String)
   * @see #getIndex(String)
   */
  public final void addAttribute(
      String uri,
      String local,
      String qname,
      String type,
      String val) {
    int index = super.getLength();
    super.addAttribute(uri, local, qname, type, val);
    // (index + 1) is now the number of attributes
    // so either compare (index+1) to MAX, or compare index to (MAX-1)

    if (index < MAXMinus1) {
      return;
    } else if (index == MAXMinus1) {
      switchOverToHash(MAX);
    } else {
            /* add the key with the format of "prefix:localName" */
            /* we have just added the attibute, its index is the old length */
      Integer i = new Integer(index);
      m_indexFromQName.put(qname, i);

            /* now add with key of the format "{uri}localName" */
      m_buff.setLength(0);
      m_buff.append('{').append(uri).append('}').append(local);
      String key = m_buff.toString();
      m_indexFromQName.put(key, i);
    }
    return;
  }

  /**
   * We are switching over to having a hash table for quick look
   * up of attributes, but up until now we haven't kept any
   * information in the Hashtable, so we now update the Hashtable.
   * Future additional attributes will update the Hashtable as
   * they are added.
   */
  private void switchOverToHash(int numAtts) {
    for (int index = 0; index < numAtts; index++) {
      String qName = super.getQName(index);
      Integer i = new Integer(index);
      m_indexFromQName.put(qName, i);

      // Add quick look-up to find with uri/local name pair
      String uri = super.getURI(index);
      String local = super.getLocalName(index);
      m_buff.setLength(0);
      m_buff.append('{').append(uri).append('}').append(local);
      String key = m_buff.toString();
      m_indexFromQName.put(key, i);
    }
  }

  /**
   * This method clears the accumulated attributes.
   *
   * @see org.xml.sax.helpers.AttributesImpl#clear()
   */
  public final void clear() {

    int len = super.getLength();
    super.clear();
    if (MAX <= len) {
      // if we have had enough attributes and are
      // using the Hashtable, then clear the Hashtable too.
      m_indexFromQName.clear();
    }

  }

  /**
   * This method sets the attributes, previous attributes are cleared,
   * it also keeps the hashtable up to date for quick lookup via
   * getIndex(qName).
   *
   * @param atts the attributes to copy into these attributes.
   * @see org.xml.sax.helpers.AttributesImpl#setAttributes(Attributes)
   * @see #getIndex(String)
   */
  public final void setAttributes(Attributes atts) {

    super.setAttributes(atts);

    // we've let the super class add the attributes, but
    // we need to keep the hash table up to date ourselves for the
    // potentially new qName/index pairs for quick lookup.
    int numAtts = atts.getLength();
    if (MAX <= numAtts) {
      switchOverToHash(numAtts);
    }

  }

  /**
   * This method gets the index of an attribute given its uri and locanName.
   *
   * @param uri the URI of the attribute name.
   * @param localName the local namer (after the ':' ) of the attribute name.
   * @return the integer index of the attribute.
   * @see org.xml.sax.Attributes#getIndex(String)
   */
  public final int getIndex(String uri, String localName) {
    int index;

    if (super.getLength() < MAX) {
      // if we haven't got too many attributes let the
      // super class look it up
      index = super.getIndex(uri, localName);
      return index;
    }
    // we have too many attributes and the super class is slow
    // so find it quickly using our Hashtable.
    // Form the key of format "{uri}localName"
    m_buff.setLength(0);
    m_buff.append('{').append(uri).append('}').append(localName);
    String key = m_buff.toString();
    Integer i = (Integer) m_indexFromQName.get(key);
    if (i == null) {
      index = -1;
    } else {
      index = i.intValue();
    }
    return index;
  }
}
